Set material density [kg/m³] instead of mass [kg]
I found the solution, it is directly in blender itself.
Horizontal menu bar &gt; Object &gt; Rigid Body &gt; Calculate Mass
As you can see here on the screenshot:

https://blender.stackexchange.com/a/137448/99511
Bad thing is that you need to do it every time you change the side of the object. It is not updated automatically.